Liquid dye lasers offer considerable promise for many applications, including isotope separation, photochemistry, pollution detection and spectroscopy. Dye lasers differ from the more familiar gas and solid state lasers primarily in that they employ, as an active medium, a fluid dye solution. The dye solution comprises a solvent such as an organic solvent and/or water and a solute of an organic dye material. Typical dyes have a molecular weight in the range between 200 and 1000 and are used in concentrations on the order of 10.sup.-4 moles per liter. A primary advantage of dye lasers over conventional gas and solid state lasers is that the dye laser output can be tuned over a broad range from the near ultraviolet to the near infrared.
Dye reservoir systems are required with liquid dye lasers in order to continuously provide the laser with replenished dye solution. Radiation from the laser excitation source decomposes both the solvent and the solute of the solution, producing by-products which degrade the laser performance. Specifically, the by-products, which typically have molecular weights in excess of about 100, degrade the laser performance by (1) absorbing laser light, (2) quenching excited states, and (3) absorbing excitation light. In order to avoid such degradation, the laser is provided with a reservoir of dye solution, and fresh dye solution is continuously pumped through the laser cavity. The exposed solution is filtered to selectively remove by-products, and it is then returned to the reservoir. Such filtration systems must distinguish between dye molecules and other contaminates, removing the latter but retaining the former in the solution flow system. Any loss of dye is thus to be avoided since the system is provided with only a specific amount of dye at a predetermined concentration.
The difficulty with typical prior art reservoir systems, however, is that they require large reservoirs of dye solution. In many applications, such as in portable systems, space and weight are at a premium. However, conventional dye solution reservoirs, which can require a capacity of ten gallons or more, are the most voluminous part of the dye laser system. Accordingly, there is a need for a more compact reservoir system.